1. Field of the Invention
The invention relates to a method for determining the purity of treated used glass prior to recycling for determining the purity of the treated used glass, in which a sample quantity is removed from a stream of treated used glass and any foreign bodies still contained therein are separated into sorted fractions respectively comprised of non-ferrous metals and opaque foreign materials such as ceramic and porcelain particles and stones, the sorted fractions are weighed and the weight of the sorted fractions is related to the weight of the whole sample quantity.
2. Description of the Prior Art
The treatment of used glass must ensure a high degree of freedom from foreign materials. Thus, the treated used glass may contain per ton not more than 20 g of opaque foreign particles or bodies such as ceramics, porcelain or stones and not more than 5 g of non-ferrous metals. These high degrees of purity are required because presently more than 95 per cent of used glass is added to a melt for producing new glass. These high degrees of purity have to be guaranteed by the processors of used glass and have to be proved by samples of the treated used glass. As the sampling is made at regular intervals during the treatment and as large sample amounts are required due to the low amount of permissible impurities, in particular ceramics, stones, porcelain and non-ferrous metals, the analysis of the treated used glass is very complex and expensive. This is further exacerbated by the fact that the samples presently have to be evaluated manually.
In the conventional method, the foreign materials, which are sorted into fractions respectively comprised of non-ferrous metals and opaque foreign materials such as ceramics, porcelain, stones or the like, are removed from each sample quantity, thereafter weighed and their weight is related to that of the sample quantity.